I am looking for some microcontrollers with USB capabilities and some are said to have USB 2.0 HS Host/Device with PHY others say USB 2.0 HS OTG Host/Device with PHY.

I am not a specialist in the USB specifications, so I wonder, choosing a OTG part will have any set backs or limitations?

I am expecting OTG parts to behave just as regular USB parts do, so if I program my part to act as host, and I connect it with a regular USB 2.0 device, they will connect as usual.

  • \$\begingroup\$ What USB capabilities you require.....do you intend to connect it to PC to do something....or do u want some other USB device like USB drives to be connected to this and accessed......?Based on capabilities/application you can select host or device/// \$\endgroup\$
    – user19579
    Commented Sep 17, 2014 at 6:37
  • \$\begingroup\$ Both..I want to connect it to a PC and to other stuff. \$\endgroup\$
    – mFeinstein
    Commented Sep 17, 2014 at 17:30

1 Answer 1


Here are a couple differences between a USB 2.0 host and a USB 2.0 OTG host.

  • Support for high and low speed communication are optional for the OTG host
  • Support for hubs are optional on the OTG host. If hubs aren't supported then you're limited to only one device on that host.
  • Normal hosts are required to be able to supply at least 100mA where as OTG hosts are only required to be able to supply 8mA.
  • The OTG host can tun off VBUS.
  • OTG uses an AB port that can take both types of USB cable.

You can see a lot the requirements of a conventional USB host are optional on the OTG host. The exact capabilities would depend on how the microcontroller implements it. If the OTG host you pick meets your requirements, there shouldn't be any noticeable difference between the two. On the software side of things, the only difference you should see is the added capability to switch between host and device mode on the OTG part.

  • \$\begingroup\$ Ok great so I just have to keep an eye open on speed and hubs, since current limit is my design that will say how much can be drawn... \$\endgroup\$
    – mFeinstein
    Commented Sep 17, 2014 at 17:29

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